Switch mechanism



April 30, 1929. A. w. BURKS SWITCH MECHANISM 2 SheetsSheet Filed Dec. 1, 1921 w 65 WM W W April 30, 1929. A BURKS 1,710,859

SWITCH MECHANISM Filed Dec. 1, 1921 2 Sheets-Shem 3 Invenfa r." firkur fiwrks,

Patented Apr. 30, 1929.

UNITED STATES ARTHUR W. BURKS, F DECATUR, ILLINOIS.

SWITCH MECHANISM.

Application filed December This invention relates to improvements in electrical switch mechanism, and more particularly to mechanism adapted automatically to control a circuit in accordance with varia tions in certain conditions, such as fluid pressure. I

An object of the invention is to provide a positive, accurate and simple mechanism which will maintain a circuit closed under minute variations of the actuating pressure, but which will quickly snap open the circuit when the predetermined degree of pressure is present.

Another object of theinventionistoprovide a mechanism in which there is present, under minute pressure Variations, a relative movement of the contacts, without separation, thus affording a frictional engagement between the surfaces of the stationary and movable contacts and maintaining clean contact surfaces. A still further object is to afford a considerable pressure of the movable contact against the surface of the stationary contact during the pressure fluctuating movements abovementioned.

An additional object of the invention is to maintain a constant and unvarying degree of opposition, on the part of the main spring, to the movement of the fluid responsive element.

The above and other objects of the invention which reside in the construction and arrangement of parts later to be described, will be more clear after a reading of the following description of the embodiment of the inven- 33 tion shown in the accompanying drawings.

In the drawings Fig. 1 is a front elevational view,

Fig. 2 is an elevational view taken at right angles to Fig. 1 with a portion of the frame broken away,

Fig. 3 is a vertical cross sectional view showing the position of the parts when the circuit is closed,

Fig. 4 is a view'similar to Fig. 3 showing the relation of the parts when the circuit is open, and

Fig. 5 is a detail view showing the position of the'lever mechanism when the toggle is thrown to an intermediate or dead-center posit'ion.

Referring to the drawings for a more detailed-description, 10 indicates the substantially ring-shaped base of a frame which is secured, as by screws 11, to a base plate 12 having on its under face a centrally dis 1, 1921. Serial no. 519,125.

posed and internally threaded nipple 13 through which may be exerted against a flexible diaphragm 14 clamped between the base plate and the base of the frame the pressure of a fluid or other actuating medium.

Extending upwardly from two substantial- 1y diametrically opposite positions around the base 10 are two side strips 15 connected at their upper ends by a cross-web 16. Within the frame, upon a cross pin 17 are fulcrumed a pair of bell crank levers 18, 18 slightly spaced apart and carrying between them at the end of their short arms a needle bearing stud 19, which is secured to each lever by means of pins 20. The under-face of the stud is provided with a substantially conical cavity to receive a diaphragm pressure element which, in the present instance, comprises a boss 21 formed integral with a plate 22 mounted within the base 10 upon the diaphragm. The upper end of the stud fits within abearing cavity 23 in the under-face of a plunger 24 extending-upwardly into a cylinder 25, the plunger being pressed downwardly by a coil spring 26 surrounding the.

cylinder and the plunger; the spring abut ting at its upper end a flange 27 upon the cylinder, and at its lower end a flange 28 upon the plunger. The cylinder is held in position by an adjusting screw 29 passing through the web 16 of the frame into a recess 30 in the top of the cylinder. Obviously, the coil 4 The long arms of the levers 18, 18 extend outwardly and upwardly, and are connected together by cross pins 31, 32. The pin 32 extends through a slot 33 extending lengthwise of an arm 34 which carries, at its upper end in an insulating bushing 35, a movable contact bar 36. From an inspection of Fig.

1 it will be noted that the arm 34 is formed i of two parallel strips 34 and 34 connected together at their lower ends by a pin 37, the contact bar 36 serving to hold together the strips at their upper ends. Pivotally secured to the pin 37 between the strips of the arm 35 is a second arm 38, which is forked, and straddles the pin 31. A'coil spring'39 surrounds the arm 38, abutting shoulders 40 upon the arm and the pin 31. It Wlll be noted that the two arms 34 and 38, together, form a toggle, and the spring 39, when the parts 44 extending through the contactsinto a web 16 depending from the under face of the top wall 16. Binding posts may be positioned above the stationary contacts 1n the top wall of the frame.

The stationary contacts 42, 43 are insulated from the frame, as indicated at 46, and are also insulated by strips 47 from stops 48 located between the contacts and the web 16. The meeting faces of the stationary contacts and the stops are cut away, as shown in Fig.

2, to form seats 49. The contacts and the stops, together, form a substantially U- shaped recess 49 for the ends of the movable contact bar 36.

When the circuit is closed and "the fluid pressure has not risen sufiiciently to separate the stationary and movable contacts, the parts are in the position shown in Fig. 3, with the stationary and movable contacts in engagement and the spring 39 on the lower toggle arm 38 urging the movable contact against the surface of the stationary member. Variations in the fluid pressure which are insuflicient to separate the contacts will move the lever and the toggle arms in varying distances, depending upon the amount of rise in pressure, from the position shown in Fig. 3 to the position of dead-center shown in Fig. 5. During these movements the stationary and'inovable contacts will remain in engagement, but the bar 36 will be rotated slightly, in its seat in the stationary terminals due to the pin 32 upon the levers 18, 18 engaging the side of the slot 33 in the upper-toggle arms 34 and swinging the arm outwardly about the contact bar 36 as a fulcrum. That is to say, the movement of the toggle arms 34, 34' from the position shown in Figs. 2 and 3 to the position of dead-center shown in Fig. 5 has been caused by the levers 18 urging the pin 32 against the side of the slot 33; and the contact bar 36 has no movement of translation, but merely one of rotation, since it serves. as a fulcrum for the toggle arms. It will be observed that during this movement the lower arm 38 will be pressed downwardly along the pin 31, the spring 39 being compressed as the toggle approaches dead-center, shown in Fig. 5. The pressure of this spring increases the frictional engagement between the movable contact and the surfaces of the. stationary contact, thereby serving to maintain the surfaces clean and, untarnished.

If the fluid pressure is suflicient to swing the lever 18 outwardly against the position of plunger 24 so that the toggle is moved past pin 32 engages the opposite side of the slot '33. Subsequent movement of the toggle arms takes place entirely and exclusively under action of the spring 39, and this spring action serves to impart to the contact bar 36 a movement of translation away from its seat, the bar 36 no longer serving as the fulcrum for the movement of the toggle arms 34, 34. The pin 32 being in engagement with the opposite side of the slot 33, as shown in Fig. 4, serves as a stop or fulcrum for the movement of the upper arm, and as the spring 39 expands the upper arm is swung about the pin 32 and the contact bar 36 is quickly separated from the stationary terminals 42. It should be observed that the levers '18, 18 serve to actuate the toggle only while it is being moved to dead-center, since all movement of the toggle, once the same has been carried past dead-center, results from the spring 39 which has been compressed. This spring actuates the toggle and the movable contact independently of the lever and diaphragm, and in a very quick manner. The break be tween the stationary and movable contacts is a quick one. but all movement up to a point of dead-center between the points and the contacts has been without separation of the contacts, the movable contact 36, during this portion of the toggle movement having merelybeen rotated slightly in its seat. The movable contact, it will'be noted, is carried by one of the links of the toggle and during the movement of the toggle to dead-center from either of the toggles extreme positions, the stationarycontact serves as a fulcrum for the toggle while the movable contact is at the same time rotated in its seat in the stationary contact. This movement of rotation takes place under the constantly increasing pressure of the spring 39, and thus it will be obvious that there is present, during such motion a considerable degree of friction be- I arrests 7 when the spring acts directly upon the diaphragm theopposition of the spring to the diaphragm movement increases as the diaphragm is moved upwardly by' the fluid pressure. It. has been found to be highly desirable that the opposition of this spring be maintained as nearly constant as possible, and I, therefore, counteract the increasing tension and consequent increasing opposition of this spring to the diaphragm by positioning the spring so that it will act upon the diaphragm through the bell crank levers 18 rather than directly upon the diaphragm. It will be obvious from an inspection of Fig. 4 that the spring 26, in pressing downwardly, acts against the lower end of the levers, and before its pressure reaches the diaphragm it must swing the bell crank levers about their fulcrum 17. This arrangement counteracts, to some extent, the increased pressure exerted by the spring on being compressed, and maintains more nearly constant the action of the spring against the diaphragm as the diaphragm is raised.

It should be understood that the invention is by no means limited to the specific arrangement of parts and the identical construction shown in the accompanying drawings, and herein described, the disclosure in its details being illustrative in its character, and in no sense restrictive of the invention.

1 claim:

1. In a device of the class described, a stationary contact, a movable contact cooperating with the stationary contact and actuating means for the movable contact comprising a lever, a pair of pivotally connected links forming a toggle mechanism carried by the lever, one of saidlinks carrying said movable contact and the toggle mechanism being movable to dead center by said lever during its initial movement, the movement of the toggle to dead center producing a movement of said movable contact Without separation of the same from said stationary contact, and spring means associated with said toggle mechanism adapted to be tensioned by said initial movement to press together said contacts, the stationary contact during movement of the toggle to dead center serving as a fulcrum for the movable contact, said spring means upon further movement of said lever actuating said toggle and separating the contacts independently of the lever.

2. In a device ofthe class described, a stationary contact, a movable contact cooperating therewith and actuating means for the movable contact comprising a lever, a pair of links forming a toggle mechanism mounted on said lever, one of said links carrying said movable contact, said toggle mechanism being movable 'to dead center upon initial movement of said lever, spring means associated with, said toggle mechanism adapted to tension said contact carrying link when the toggle mechanism is moved to dead center and to press together said contacts, said link being free on the lever for longitudinal movement as well as pivotal movement when the toggle mechanism is moved to dead center, and the stationary contact serving as a fulcrum for the movable contact during movement of the toggle to dead center, and the spring means serving either to separate said contacts independently of said lever upon further lever movement or to maintain the contacts in engagement in the absence of further movement of the lever.

3. In a device of the class described, a stationary contact and a movable contact cooperating therewith, means for actuating said movable contact comprising a lever having two extremes of movement, a pair of links forming a toggle carried by the lever and adapted to be moved to dead center upon initial movement of the lever from either ex treme position, said movable contact being mounted upon one of the links of the toggle, said links both being free to move longitudinally as well as pivotally when the toggle is moved to dead center and spring means tensionable during the initial movement of said lever serving to urge the link longitudinally and to press the movable contact against the stationary contact, said spring means being releasable upon movement of the toggle mechanism past dead center and serving to separate said contacts independently of the lever.

i. In a device of the class described, a stationary contact and movable contact, and means for actuating said movable contact comprising a lever having two extreme positions, a pair of links carried by said lever forming a toggle mechanism, means on said lever afiording an independent pivotal mounting for each link, the links having longitudinal movement as well as pivotal movement when the toggle moves to dead center, said stationary contact being mounted upon one of said links, a spring associated with said linksadapted to be tensioned when the toggle mechanism is moved to dead center and to press said movable contact during said movement against said stationary contact, said spring being released upon movement of the toggle past dead center and serving to separate said contacts independently of said lever.

5. ltn a device of the class described, a stationary contact, a movable contact, and means for actuating said movable contact comprising a lever having two extreme positions, an

arm movably mounted upon said lever and carrying said movable contact, a second arm pivotally connected to said first mentioned arm and movably mounted upon said lever to form a toggle with said first mentioned arm, a coil spring connected to one of said arms and adapted to be placed under tension when the arms are moved to dead center, said toggle being movable to dead center by said lever upon its initial movement, said movable contact, during said initial movement, being moved over the face of said stationary contact and pressed thereagainstby said spring tension, but not being separated therefrom, and said spring being adapted to separate said contacts independently of said lever when said toggle has been moved past dead center in one direction.

6. In a device of the class described, a stationary contact, a movable contact, and means for actuating said movable contact comprising a lever, a pair of links on said lever pivotally connected and forming a toggle mechanism which is movable to dead center upon initial movement of said lever, at least oneof said links being longitudinally movable when the toggle mechanism is moved to dead center, said movable contact being carried by said link and spring means associated with said toggle mechanism adapted to be tensioned when said mechanism ismoved to dead center and to press said movable contact against the stationary contact, the movable contact having a rotative movement on said stationary contact during movement of the toggle mechanism to dead center, but being held by said spring means again t translative movement, said spring being adapted to separate said contacts independently'ofsaid lever when the toggle is moved past dead center.

7. In a device of the class described, a stationary contact, a movable contact, and. means for actuating said movable contact comprising a lever, a pair of links carried by said lever forming a toggle mechanism which is movable to dead center upon initial movement of said lever, both of said links being freely mounted on said lever for longitudinal as well as pivotal movement, said movable contact being mounted on one link, spring means associated with said links adapted to be compressed when the toggle is moved to dead center, and to press said movable contact against said stationary contact, which serves as a fulcrum for the movable contact, during movement of the toggle to dead center, the spring being adapted toseparate said contacts independently of the lever when the I toggle is moved past the dead center.

8. In a device of the class described, a stationary contact, a movable contact cooperating with the stationary contact, and actuating means for the movable contact comprising a lever, a toggle mechanism comprising a pair of pivotally connected links movable to dead-center vby said lever during its initial movement, the said movable contact being carried by one of the links of said toggle mechanism, the stationary contact serving as a fulcrum for the movable contact member during the movement of the toggle links to dead-center, the link of the toggle not carrying the contact having a pivot on said lever, and spring means connected to saidtoggle and adapted to be tensioned by said initial movement and to press together said contacts during said movement of the toggle to dead center, said spring means upon further movement of said lever actuating said toggle and separating the contacts independently of the lever, said lever having a loose actuating connection with said toggle.

9. In a device of the class described, a stationary contact, a movable contact cooperating with the stationary contact, and actuating means for the movable contact comprising a lever, a toggle mechanism comprising a pair of pivotally connected links movable to dead-center by said lever during its initial movement, the said movable contact being carried by one of the links of said toggle mechanism, the stationary contact serving as a fulcrum for the movable contact during movement of the toggle links to dead-center, the link not carrying the contact having a pivot on said lever and being both pivotally and longitudinallymovable, the movement of said toggle mechanism to dead-center producing a relative movement of said contact members without separation, and sprin means connected to said toggle and adapted during said movement to press together said contacts, said spring means upon further movement of said lever actuating said toggle and separating the contacts independently of the lever. A

10. In a device of the class described, a movable contact, a stationary contact having a seat for said movable contact, and actuating means for said movable contact comprising a lever, a toggle mechanism comprising a pair of links connected to said lever and movable to dead center upon initial movement of the lever, said movable contact being carried by one of the links of the toggle and rotating upon said seat without separation therefrom my hand.

ARTHUR W. BURKS.

to be tensioned by said initial movement and 

